Support arrangement for the electrodes of an electric discharge device



1968 v. A. HEATHCOTE 3,409,794

SUPPORT ARRANGEMENT FOR THE ELECTRODES OF AN ELECTRIC DISCHARGE DEVICE Filed Dec. 22, 1965 .0 1 u 22 25 E ID 22 2 449 I5 3 6 I YNYe-N K United States Patent 3,409,794 SUPPORT ARRANGEMENT FOR THE ELECTRODES OF AN ELECTRIC DISCHARGE DEVICE Vincent A. Heathcote, Fulham, London, England, as-

signor to The M-O Valve Company Limited, London, England, a British company Filed Dec. 22, 1965, Ser. No. 515,578 Claims priority, application Great Britain, Dec. 31, 1964, 53,039/ 64 Claims. (Cl. 313261) ABSTRACT OF THE DISCLOSURE This invention relates to electric discharge devices.

The invention relates particularly to electric valves of the kind including at least two generally tubular electrodes which are disposed one within the other with their axes coincident or parallel.

It is an object of the present invention to provide an electric discharge device of the kind specified wherein there is utilised a simple arrangement for supporting said two electrodes accurately in position relative to one another.

According to the present invention, in an electric discharge device of the kind specified said two electrodes are supported with respect to one another by means including at least two rods whose major axes extend in directions which are at an appreciable angle to one another and which are parallel to a plane transverse to the axes of said electrodes, each rod fitting slidingly through at least one aperture in each of two members which are respectively rigidly fixed to said two electrodes, so that relative movement between said electrodes at least in a direction perpendicular to the axes of said electrodes is substantially prevented.

Preferably said two electrodes are separately supported with respect to one another at each end by means as specified in the preceding paragraph.

Said plane is suitably perpendicular to the axes of said electrodes.

Said two rods are suitably arranged so that their major axes extend in directions at right angles to another.

One arrangement in accordance with the invention will now be described, by way of example, with reference to the accompanying drawing in which:

FIGURE 1 is a sectional side elevation of a vane-type magnetron employing double ring strapping; and

FIGURE 2 is a perspective view illustrating the arrangement used for supporting the cathode with respect to the anode in the magnetron shown in FIGURE 1.

Referring now to FIGURE 1, the magnetron has a sealed metal envelope comprising a tubular metal member 1 across the ends of which are respectively sealed two metals discs 2. The central portion of the interior of the envelope is divided into a series of compartments by a number of similar metal vanes 3 which extend radially inwards from the internal surface of a central portion of the member 1 which portion is of reduced internal diameter, this portion of the member 1, together with the vanes 3, constituting the anode of the magnetron. Each vane 3 3,409,794 Patented Nov. 5, 1968 lies in a different plane including the axis of the envelope, and the vanes 3 are electrically connected together in conventional manner at each end of the anode by means of two metal rings 4 of different diameters.

Power is extracted from the magnetron via a lead 5 which extends radially with respect to the envelope through an aperture in the member 1, and at its inner end is connected to the outer ring 4 at one end of the anode.

The magnetron further includes a tubular cathode 6 which is disposed coaxially within the envelope. Within the cathode 6 is disposed a heater 7 in the form of a helical coil of wire, the heater 7 being supported between the ends of two wire leads 8 which are bent at right angles and are sealed insulatingly through the tubular member 1. The external surface of the part of the cathode 6 lying within the volume defined by the inner edges of the vanes 3 constitutes the emissive surface of the cathode 6 and at each end the cathode 6 projects beyond the anode, the cathode 6 being supported accurately coaxial with respect to the anode at each end by an arrangement described in detail below.

Referring now to FIGURES l and 2, at each end the cathode 6 is secured through an aperture formed centrally in a flanged square metal plate 10 lying in a plane perpendicular to the axis of the cathode 6. Along each of its edges the plate 10 is provided with a flange 11 or 12 disposed in a plane perpendicular to the plane of the plate 10, the flanges 11 on one pair of opposite edges of the plate 10 extending away from the plate 10 in the opposite direction to the flanges 12 on the other pair of opposite edges of the plate 10.

The plate 10 is supported on three ceramic rods 13, 14 and 15 which, in turn, are supported on a flanged annular member 16 formed from sheet metal. The member 16 is bolted at four equally spaced positions to the adjacent end of the central portion of the member 1, the bolts 17 being fitted with spacers 18 so that the member 16 is spaced from the adjacent end of the anode and is disposed in the same plane as the plate 10. The member 16 is provided with four flanges 19 and 20 at equally spaced positions around its outer edge, each flange 19 or 20 being parallel to, and in register with, the nearest flange 11 or 12 on the plate 10; the member 16, like the plate 10, is thus provided with two pairs of diametrically opposite flanges 19 and 20, which extend away from the member 16 in opposite directions.

The member 16 also has formed in it four slits 21, each of which extends into the member 16 from its outer edge adjacent a different one of four apertures 22 through which the bolts 17 fit. Each slit 21 turns around the associated aperture 22, and extends a short distance along the member 16. The purpose of these slits 21 is to take up differences in thermal expansion of the members 1 and 16.

The ceramic rod 13 fits slidingly through two apertures formed respectively in the flanges 11 lying on the side of the plate 10 remote from the anode and through two apertures formed respectively in the corresponding flanges 19 on the member 16, the positions of the apertures being such that the rod 13 lies to one side of the cathode 6 and extends in a direction parallel to the plane of the plate 10. The other two rods 14 and 15 fit slidingly through apertures formed in the flanges 12 and 20, the apertures being positioned so that the rods 14 and 15 lie one on each side of the cathode 6 and extend parallel to the plane of the plate 10 in directions at right angles to the rod 13.

The length of each of the rods 13, 14 and 15 is just less than the internal diameter of the adjacent part of the member 1, thereby preventing the rods 13, 14 and 15 from falling out of the apertures.

The rods 14 and 15 also carry a centrally apertured 3 rectangular flanged-metal plate 23 to one main face of which is attached a similarly apertured metal disc 24 which has a diameter slightly greater than the length of the longer sides of the plate 23 and serves as an end hat for the cathode 6. The rods 14 and 1S fit slidingly through apertures formed in flanges 25 provided on the shorter edges of the plate 23, the flanges 25 extending from the plate 23 in a direction away from the anode so that the disc 24 lies on the side of the rods 14 and 15 nearer the anode, close to the anode, the cathode passing through the apertures in the plate 23 and the disc 24. This method of mounting the cathode end hats has the advantage that the end hats are to a large extent thermally isolated from the cathode 6, thus reducing the possibility of thermionic emission from the end hats.

It will be appreciated that the arrangement described above byway of example issimple to manufacture and assemble and that due to the geometrical constraints of thelarrangement, the anode and cathode 6 are accurately maintained coaxial, provided the rods 13, 14 and 15 are a good fit in the apertures in the flanges 11, 12, 17 and 18. Final adjustment of the position of the cathode 6 with respect to the anode may be made by differential tightening of the bolts 17.

It will be understood that in otherarrangements more than three or only two rods may be utilised at one or both ends of a pair of electrodes, although of course an arrangement in accordance with the invention must include at least two rods which extend in directions at an angle to one another. In addition, while in the arrangement described by way of example, the rods are offset from the axis of the cathode 6 to facilitate connection to the heater 7, this need not be the case in other arrangements in accordance with the invention.

I claim:

1. An electric discharge device comprising:

a. sealed envelope;

a pair of tubular electrodes housed within the envelope;

and

a support arrangement for supporting said two electrodes one within the other with their axes parallel, the support arrangement comprising:

a pair of members which are respectively rigidly fixed to said two electrodes; and

at least two rods whose major axes extend in directions which are at an appreciable angle to one another and which are parallel to a plane transverse to the axes of said electrodes, eachrsaid rod fitting slidingly through at least one aperture in each of said two members so that relative movement between said two electrodes, at least in a direction perpendicular to the axes of said electrodes, is substantially prevented.

2. An electric discharge device according to claim 1 wherein the major axes of said rods extend in directions substantially at right'angles to one another and said plane is perpendicular to the axes of said electrodes.

3. An electric discharge device according to claim 1 wherein said two electrodes are an anode and a cathode respectively, and the cathode end hat is supported from at least one of said rods.

4. An electric discharge device according to claim 1 incorporating a said support arrangement at each end of said pair of electrodes.

5. An electric discharge device according to claim 1 wherein each said rod fits slidingly through at least two spaced-apart apertures in each of said two members.

References Cited UNITED STATES PATENTS 2,537,824 1/1951 Hagstrum 31539.67 X 2,617,079 11/1952 McNall 3l5-39.57 2,617,956 11/1952 Hamvas 313261 X JOHN W. HUCKERT, Primary Examiner. A. '1. JAMES, Assistant Examiner. 

